Re: [81attendees] What is it at the bottom of restaurant receipts?

["Worley, Dale R (Dale)" <[e-mail]>]

Comparing a few receipts, I've so far discovered:

There are always 12 dingbats in the row.

There are never duplicates on a single receipt.  This suggests that the dingbats are not a direct transcription of information, but rather statistically random.

One can easily stack 5 receipts (60 dingbats) and see no duplicates.  This suggests (via the birthday paradox) that there are more than 60^2 = 3600 dingbats that are commonly used.

My current guess is that there are 4096 dingbats representing 12 bits each, and the line represents 12 * 12 = 144 bits that are either a hash or a digital signature of the data in the hash.  The dingbats are probably to be visually compared by a human with a similar display that is computed by a government device from the data on the receipt.

Curiously, on one receipt I have, the dingbat row consists of a sequence of 6 dingbats repeated twice, which seems to me to be very unlikely.

Dale